The patent art evidences activity in this area and this discussion will be limited to the most relevant patents. Thus U.S. Pat. No. 3,146,130 teaches the impregnation of porous electrodes with a solution of an ammonium complex silver prepared by dissolving a silver compound in a nitrogen-containing solvent and heating to evaporate the solvent. U.S. Pat. No. 2,934,460 to Ramadanoff concerns a method for impregnating carbonaceous brushes with silver and silver sulfide in a precipitate such as acetone or ethylene diamine; heating to precipitate silver nitride in situ rapidly and then further heating the brush to reduce the silver nitrate to silver. U.S. Pat. No. 4,220,884 describes a method of making a carbon contact brush by melting a metal such as tin or an alloy thereof with lead, zinc and silver; immersing a porous carbon body therein to impregnate it with molten metal and removing the body from the molten metal to solidify the metal therewithin.
None of these patents suggest or hint at the incorporation of the metal with graphitic particles and pitch prior to shaping and cannot produce the same articles.